The term transparent panel as used herein includes a sheet of transparent material, a laminate of transparent materials or an assembly of transparent materials, such as glass or plastics, for example, acrylic sheets or polycarbonate sheets and including flexible materials such a polyester film or polyvinyl chloride film and also includes a transparent panel having an obscure or other distorted image effect. Similarly, the term translucent panel is intended to include a sheet of translucent material, a laminate of translucent materials such as glass or plastics, for example, acrylic sheets or polycarbonate sheets and including flexible materials such as polyester film, polyvinyl chloride film, paper, fabric or other material.
The incorporation of an opaque pattern on or into particular types of transparent panels in order to create unidirectional vision is already known in the construction of transparent walled squash courts, as seen in copending application Ser. No. 545,166 of Oct. 25, 1983. These panels include a continous and opaque pattern applied in single color, or with the pattern appearing one color from one side of the panel but another color from the other side to enhance the one-way vision effect when one side of the panel is illuminated more than the other side. A single color pattern is normally white or a light color and a two color pattern is normally arranged to be white or light color on the one side of the panel and black or dark color on the other side of the panel. The patterns are superimposed with exact or near exact registration, an arrangement which enhance the clarity of vision from the other side to the one side. Such materials can be used to enable spectators or television cameras to see through a squash court from one side while the players on the other side cannot see through the material to the other side and thus are not distracted by the crowds, etc. The pattern in such panels is normally one of small dots such that, the eye of a spectator in the audience who is at a distance from the panel cannot discern the individual elements of the pattern, the elements being too small for the eye to resolve.